I managed to borrow Saeki Chizu's book - "The Japanese Skincare Revolution" - from the library a while back. Among the various techniques introduced in her book, I felt that the 3-minute lotion mask is a cost and time saver, but yet provides good results. The principal behind this technique is to get the skin to absorb the active ingredients found in your toner/lotion and to provide hydration to your skin.
An analogy provided by Saeki Chizu.
Let's imagine that your skin is like a piece of cloth, and when two substances -soya sauce and chilli sauce - are dripped on to the piece of cloth, which one absorbs better? The most probable observation that you would notice is that the soya sauce gets absorbed into the cloth much more faster than the chilli sauce. Therefore the 3-minute mask can be used to prep the skin so that it can receive the nutrients from your face cream or serum better.
Why 3 minutes?
It is observed that it takes about 3 minutes for the toner/lotion to be absorbed into the skin. If the lotion mask is left on the face for more than 3 minutes, the cotton pad would re-absorb the toner/lotion which had penetrated into your skin. Thus, defeating the purpose of using the lotion mask technique.
Why do we need to wet the cotton?
When we wet the cotton, it helps to "soften" it, because the fibres of the dry cotton pad could have an irritating effect on our skin. Secondly, when we pour our lotion/toner on to the moist cotton pad, the moisture in the cotton pad helps to spread the lotion/toner more evenly. (Note: It does not dilute you lotion/toner and neither does it make your toner/lotion less effective)
What type of cotton wool to use?
When I first started using the lotion mask technique, I used normal facial squares. I usually have to use around 3 pieces to cover my whole face and it took me too much time to separate the facial squares into thinner pieces. Then, I noticed that Muji does sell unbleached cotton pads. The one I bought was $6.90 for 102 pieces (7cm by 9cm). I guess it's rather affordable. Considering if you use the lotion mask once a day, one packet of Muji's cotton pad could probably last you for around 3 months. And yes, it definitely took me less time to peel off the cotton pads into thinner pieces after I made the switch.
If you were to ask my opinion, I feel that normal facial squares and the ones that Muji sells work equally well, it's just that for convenience sake, it would be easier to get a larger piece of cotton pad. But it's really up to you :)
Here's a detailed video of Saeki herself demonstrating the lotion mask technique. Her Japanese-accent English has an endearing charm :)
